[PATCH] xfs: don't iunlock the quota ip when quota block allocation fails

[PATCH] xfs: don't iunlock the quota ip when quota block allocation fails

[Darrick J. Wong]

From: Darrick J. Wong <darrick.wong@oracle.com>

In xfs_qm_dqalloc, we join the locked quota inode to the transaction we
use to allocate blocks.  If the allocation or mapping fails, we're not
allowed to unlock the inode because the transaction code is in charge of
unlocking it for us.  Therefore, remove the iunlock call to avoid
blowing asserts about unbalanced locking + mount hang.

Found by corrupting the AGF and allocating space in the filesystem
(quotacheck) immediately after mount.  The upcoming agfl wrapping fixup
test will trigger this scenario.

Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
---
 fs/xfs/xfs_dquot.c |    2 --
 1 file changed, 2 deletions(-)

diff --git a/fs/xfs/xfs_dquot.c b/fs/xfs/xfs_dquot.c
index 43572f8..2410acc 100644
--- a/fs/xfs/xfs_dquot.c
+++ b/fs/xfs/xfs_dquot.c
@@ -394,8 +394,6 @@ xfs_qm_dqalloc(
 error1:
 	xfs_defer_cancel(&dfops);
 error0:
-	xfs_iunlock(quotip, XFS_ILOCK_EXCL);
-
 	return error;
 }
 

Re: [PATCH] xfs: don't iunlock the quota ip when quota block allocation fails

[Darrick J. Wong]

On Thu, Feb 22, 2018 at 03:04:35PM -0800, Darrick J. Wong wrote:
> From: Darrick J. Wong <darrick.wong@oracle.com>
> 
> In xfs_qm_dqalloc, we join the locked quota inode to the transaction we
> use to allocate blocks.  If the allocation or mapping fails, we're not
> allowed to unlock the inode because the transaction code is in charge of
> unlocking it for us.  Therefore, remove the iunlock call to avoid
> blowing asserts about unbalanced locking + mount hang.
> 
> Found by corrupting the AGF and allocating space in the filesystem
> (quotacheck) immediately after mount.  The upcoming agfl wrapping fixup
> test will trigger this scenario.
> 
> Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>

Realized I had a whole pile of other fixes to send out, so ignore this
for now.

--D

> ---
>  fs/xfs/xfs_dquot.c |    2 --
>  1 file changed, 2 deletions(-)
> 
> diff --git a/fs/xfs/xfs_dquot.c b/fs/xfs/xfs_dquot.c
> index 43572f8..2410acc 100644
> --- a/fs/xfs/xfs_dquot.c
> +++ b/fs/xfs/xfs_dquot.c
> @@ -394,8 +394,6 @@ xfs_qm_dqalloc(
>  error1:
>  	xfs_defer_cancel(&dfops);
>  error0:
> -	xfs_iunlock(quotip, XFS_ILOCK_EXCL);
> -
>  	return error;
>  }
>  
> --
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